[JSC] String serialization of functions doesn't match Blink / Gecko

[Chris Dumez]

[JSC] String serialization of functions doesn't match Blink / Gecko:
https://jsbin.com/zomehipuho/edit?html,output

f = function(){ }
"" + f is "function(){ }" in Gecko and Blink
"" + f is "function (){ }" in WebKit

Gecko and Blink uses the format exactly as provided when constructing the function.
WebKit enforces a space between function and (), even if the original input didn't have one.

This is causing the following WPT test to fail:
imported/w3c/web-platform-tests/webstorage/storage_string_conversion.window.html

[Radar WebKit Bug Importer]

<rdar://problem/97445158>

[Colin Vidal]

Pull request: https://github.com/WebKit/WebKit/pull/14704

[EWS]

Committed 265284@main (55ae3a1d4de3): <https://commits.webkit.org/265284@main>

Reviewed commits have been landed. Closing PR #14704 and removing active labels.